Removal of phosphate from water by activated carbon fiber loaded with lanthanum oxide

Phosphate removal from wastewater is very important for the prevention of eutrophication. Adsorption of phosphate from water was investigated using activated carbon fiber loaded with lanthanum oxide (ACF-La) as a novel adsorbent. The effects of variables (La/ACF mass ratio, impregnation time, activation time, and activation temperature) have been studied by the single-factor method. Response surface methodology (RSM), based on three-variable-three-level Box-Behnken design (BBD), was employed to assess the individual and collective effects of the main independent parameters on the phosphate removal. The optimal conditions within the range studied for preparing ACF-La were found as follows: La/ACF mass ratio of 11.78%, activation time of 2.5h and activation temperature at 650°C, respectively. The phosphate removal using the ACF-La prepared under the optimal conditions was up to 97.6% even when the phosphate concentration in water was 30 mgP/L, indicating that ACF-La may be an effective adsorbent. The results from Fourier transform infrared (FT-IR) spectroscopy and change of pH values associated with the adsorption process revealed that the probable mechanism of phosphate ions onto ACF-La was not only ion exchange and coulomb interaction, but also a result of Lewis acid-base interaction due to La-O coordination bonding.     

活性炭负载银吸附剂的制备与脱除苯并噻吩的研究

采用浓硝酸氧化改性的活性炭为载体负载金属Ag制备了Ag/AC系列吸附剂,并进行了模型柴油中苯并噻吩(BT)的吸附脱除性能研究。采用N2吸附、SEM、FT-IR及XRD技术对吸附剂进行了表征。结果表明,氧化改性增加了活性炭表面酸性基团,有利于脱除弱碱性的BT。以HNO3氧化改性后的活性炭为载体负载AgCl所制备的吸附剂具有最高脱硫率达91.8%。最后探讨了AgNO3在活性炭上的吸附行为及金属Ag对BT的吸附脱除机理。     

Comparison of the efficiency of palladium and silver nanoparticles loaded on activated carbon and zinc oxide nanorods loaded on activated carbon as new adsorbents for removal of Congo red from aqueous solution: Kinetic and isotherm study

The adsorption of Congo red (CR) into three new adsorbents including Palladium and silver nanoparticles loaded on activated carbon (Pd NPs-AC, Ag NPs-AC) and zinc oxide nanorods loaded on activated carbon (ZnO-NRs-AC) in a batch method has been studied following the optimization of effective variables including pH, amount of adsorbents and time. The experimental data was fitted to conventional kinetic models including the pseudo first-order and second-order Elovich and intraparticle diffusion model and based on calculated respective parameters such as rate constants, equilibrium adsorption capacities and correlation coefficients. It was found that for all adsorbents the removal process follows the pseudo second other kinetic model with involvement of interparticle diffusion model. The experimental isotherm data were analyzed using the Langmuir, Freundlich, Tempkin and Dubinin and Radushkevich equations and it was found for all adsorbents that the removal process followed the Langmuir isotherm.     

Direct growth of oxide nanowires on CuOx thin film

Oxide nanowires were directly grown on a CuO(x) thin film deposited by plasma-enhanced atomic layer deposition without additional metal catalysts. Oxide nanowires would exhibit metal-catalyst-free growth on the CuO(x) thin film with oxide materials diffused on the top. Through a focused ion beam and transmission electron microscopy, we could verify that SnO(2) and ZnO nanowires were grown as single-crystalline structures just above the CuO(x) thin film. Bottom-gate structural SnO(2) and ZnO nanowire transistors exhibited mobilities of 135.2 and 237.6 cm(2) V(-1) s(-1), respectively. We anticipate that a variety of large-area and high-density oxide nanowires can be grown at low cost by using the CuO(x) thin film.     

Adsorption of cadmium by sulphur dioxide treated activated carbon

Merck carbon (1.5 mm) was treated in three ways: heating from ambient temperature to 900 degrees C in SO(2); treatment at ambient temperature in SO(2); or successive treatments in SO(2) and H(2)S at ambient temperature. All samples were then characterised and tested as adsorbents of Cd(2+) from aqueous solution. The characterisation was in terms of composition by effecting ultimate and proximate analyses and also of textural properties by N(2) adsorption at -196 degrees C. Kinetics and extent of the adsorption process of Cd(2+) were studied at 25 and 45 degrees C at pH of the Cd(2+) solution (i.e., 6.2) and at 25 degrees C also at pH 2.0. The various treatments of the starting carbon had no significant effect on the kinetics of the adsorption of Cd(2+), but increased its adsorption capacity. The most effective treatment was heating to 900 degrees C, the adsorption in this case being 70.3% more than that of the starting carbon. The adsorption increased at 45 degrees C but decreased at pH 2.0 when compared to adsorption at 25 degrees C and pH 6.2, respectively.     

Unburnt carbon from coal fly ashes as a precursor of activated carbon for nitric oxide removal

The aim of this work is to evaluate the characteristics of an activated carbon obtained from unburnt carbon in coal fly ashes to be used in the removal of NO. Carbon-rich fraction was obtained by mechanical sieving of fly ashes. The mineral matter was removed by conventional HCl and HF demineralization procedure. Activation was carried out with steam at 900 degrees C in order to develop porosity onto the sample. Characterization of samples was performed by several techniques with a main objective: to follow the mineral matter content, composition and distribution on the samples in order to better understand how to remove it from unburnt carbon in fly ashes. To study the use of this unburnt carbon as a precursor for the preparation of activated carbons for gas cleaning, the NO removal by ammonia using activated carbon as a catalyst at low temperature was performed. Results show a good performance of activated carbon in this reaction that is in relationship with BET surface area.     

DNA-directed synthesis of zinc oxide nanowires on carbon nanotube tips

This paper describes a class of three component hybrid nanowires templated by DNA directed self-assembly. Through the modification of carbon nanotube (CNT) termini with synthetic DNA oligonucleotides, gold nanoparticles are delivered, via DNA hybridization, to CNT tips that then serve as growth sites for zinc oxide (ZnO) nanowires. The structures we have generated using DNA templating represent an advance toward building higher order sequenced one dimensional nanostructures with rational control.     

生物酶/ACF复合材料降解甲醛实验研究

以具有很强吸附能力的含活性炭腈氯纶纤维(ACF)为载体,将生物酶负载于ACF制成复合材料。实验研究了制备生物酶的最佳条件,探讨了大豆蛋白在不同酸、碱、蛋白酶条件下的水解效果;测定了生物酶负载到ACF上对甲醛的去除率。采用SEM,VIS-7220表征了ACF负载生物酶的形貌变化及甲醛去除率等性能。结果表明,柠檬酸水解大豆蛋白后,其氨基氮含量可达5.4%;将其水解产物负载到ACF上,对甲醛去除率可达77%。     

SiC nanowires grown on activated carbon in a polymer pyrolysis route

β-SiC nanowires are a novel type of photocatalysts. However, they tend to be entangled together especially at high concentrations when dispersed in water, which may reduce the photocatalytic activity. It is reasonable to expect that β-SiC nanowires would provide better photocatalytic activity if they are grown on activated carbon. In the letter we report the successful synthesis of quantities of β-SiC nanowires grown on the surfaces of the activated carbon by pyrolysis of polycarbosilane at 1300 °C. The nanowires, with the diameters of 50–100 nm and the length of tens of micrometers, are composed of single crystal β-SiC along the 〈1 1 1〉 direction. Both the VLS and the VS mechanisms were employed to interpret the nanowires growth.     

负载金属对复合炭极板电极的电化学性能研究

用高比表面积活性炭作为原料,酚醛树脂为粘结剂,在高温下粘结成型制备固体超级电容器用活性炭极板,用直流恒流循环实验考察活性炭极板电极的电化学性能.在活性炭中负载不同种类金属离子,考察金属离子的电化学性能对活性炭极板比电容的影响.实验发现负载廉价金属Mn、Co、Cu可以增加放电容量,负载金属Mn的电极在700℃炭化时比电容为265 F·g-1.     

Boron removal from aqueous solutions by activated carbon impregnated with salicylic acid

In this study, the removal of boric acid from aqueous solution by activated carbon impregnated with salicylic acid was studied in batch system. pH, adsorbent amount, initial boron concentration, temperature, shaking rate and salicylic acid film thickness were chosen as parameters. Boron removal efficiencies increased with increasing adsorbent amount, temperature and pH, decreasing initial boron concentration. As thickness of salicylic acid film on activated carbon becomes thin up to 0.088nm, the efficiency increased, and then, the efficiency decreased with becoming thinner than 0.088nm of salicylic acid film. Shaking rate was no effect on removal efficiency. In result, it was determined that the use of salicylic acid as an impregnant for activated carbon led to the increase of the amount of boron adsorbed. A lactone ring, being the most appropriate conformation, forms between boric acid and -COOH and -OH groups of salicylic acid.     

金属Mn/活性炭电极材料电化学性能的研究

选用不同孔结构的活性炭采用浸渍法负载Mn金属离子,考察活性炭在负载前后的比电容变化情况。研究表明,金属Mn具有比较明显的准电容效应,其中负载金属Mn的中孔活性炭和微孔活性炭的比电容分别增加63．17％和19．69％,中孔活性炭负载金属Mn时,比电容随负载量的增加而上升;微孔活性炭负载5％时比电容最大为340．16F／g。     

Optical and photocatalytic properties of the Fe-doped TiO2 nanoparticles loaded on the activated carbon

In this work, Fe-doped (1?wt%) TiO₂ loaded on the activated carbon nano-composite was prepared using a sol-gel method. A prepared nano-composite was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), BET surface area, Fourier transform infrared spectroscopy (FTIR), photoluminescence (PL) spectroscopy and UV–Vis diffuse reflectance spectroscopy (DRS). The photocatalytic activity of the nano-composite was evaluated through degradation of synthetic textile wastewater, reactive red 198, under visible light irradiations. The XRD result indicated that the TiO₂ nano-composite contained only anatase phase. The surface area of the TiO₂ increased from 48?m²/g to 100?m²/g through the fabrication of the nano-composite. The FE-SEM results indicate that the TiO₂ particles with an average particle size of 35–70?nm can be deposited homogeneously on the activated carbon surface. DRS showed that the Fe doping in the TiO₂ -activated carbon nano-composite induced a significant red shift of the absorption edge and then the band gap energy decreased from 3.3 to 2.9?eV. Photocatalytic results indicated that the photocatalytic activity of the Fe doped TiO₂ increased under visible light irradiation in the presence of the activated carbon.     

Study of imidaclopride removal from aqueous solution by adsorption onto granular activated carbon using an on-line spectrophotometric analysis system

The removal of imidaclopride as a pesticide by granular activated carbon (GAC) and its adsorption kinetics were studied at different pH values and temperatures. In all experiments, the amount of GAC and initial concentration of imidaclopride were 2g and 25 ppm, respectively. The adsorption process was followed by an on-line spectrophotometric analysis system, which consisted of UV-spectrophotometer, a designed absorption cell, peristaltic pump and special glassy reactor. The effect of pH and temperature on adsorption was studied over 90 min adsorption periods. The obtained data were treated according to various kinetic models. The results showed that second order model was the most suitable one on the overall. The our results also showed that the adsorption rate constants for first order, second order and intraparticle diffusion models followed decreasing order: pH=7>4>10>1, T=25>35>45>55 degrees C.     

Studies on the removal of Pb(II) from wastewater by activated carbon developed from Tamarind wood activated with sulphuric acid

The low-cost activated carbon were prepared from Tamarind wood material by chemical activation with sulphuric acid for the adsorption of Pb(II) from dilute aqueous solution. The activated carbon developed shows substantial capacity to adsorb Pb(II) from dilute aqueous solutions. The parameters studied include physical and chemical properties of adsorbent, pH, adsorbent dose, contact time and initial concentrations. The kinetic data were best fitted to the Lagergren pseudo-first-order and pseudo-second order models. The isotherm equilibrium data were well fitted by the Langmuir and Freundlich models. The maximum removal of lead(II) was obtained 97.95% (experimental) and 134.22 mg/g (from Langmuir isotherm model) at initial concentration 40 mg/l, adsorbent dose 3g/l and pH 6.5. This high uptake showed Tamarind wood activated carbon as among the best adsorbents for Pb(II).     

Study on silicon carbide nanowires produced from carbon blacks and structure of carbon blacks

Silicon carbide nanowires were produced from carbon blacks at 1473 K and their microstructure was characterized by TEM, X-ray diffraction, FTIR and Raman spectroscopy. Nanowires of uniform diameters, the smallest averaging 10 nm, and narrow size distribution were obtained from graphitized carbon blacks, and their morphology depends on the properties of carbon black pecursors. High concentration of stacking faults and twins was detected. In addition to silicon carbide nanowires, a silicon carbide layer, about 20 nm thick, was formed on the surface of carbon black aggregates. The interior of the aggregates did not react and analysis of the data showed that it is composed of a mixture of amorphous carbon and small graphitic crystallites. The small lateral sizes of these crystallites remain unchanged during the graphitization process which is limited to the outer layer of the aggregates.     

Preparation and characterization of cerium oxide templated from activated carbon

The application of carbon templating to the preparation of cerium oxide and cerium–zirconium mixed oxide was investigated. Impregnation of a highly mesoporous activated carbon (Darco KB-B) with aqueous cerium nitrate, followed by calcination to remove the template, afforded nanocrystalline ceria with a surface area of up to 148 m²/g. Ceria-zirconia with surface area of 148 m²/g was similarly prepared. TEM studies on the ceria product revealed the presence of a polycrystalline phase, comprised of irregular aggregates of ceria crystallites of ca. 6.5 nm diameter. Use of activated carbon fibers (ACFs) as templates afforded ceria with a gross morphology resembling that of the fiber template. The lower surface areas (3–59 m²/g) of the resulting ceria reflect the mainly microporous nature of the ACFs; evidently the Ce nitrate solution is largely unable to penetrate the micropores. TEM showed the ceria fibers to be comprised of crystallites possessing a morphology similar to the Darco KB-B templated ceria.